Vehicle Seat and Method for Making Same

ABSTRACT

The invention relates to a vehicle seat comprising a seat portion and a backrest connected to the seat portion by a hinge mechanism. A seat element selected from among the backrest and the seat portion comprises a shell, which is made of a plastic material and the side edges of which are overmolded onto composite reinforcement inserts. Each of the inserts comprises a core perpendicular to the medium plane of the seat element, and two side flanges parallel to the medium plane of the seat element. The insert is formed by assembling two composite parts having an L-shaped cross-section and forming a portion of the core and one of the side flanges of the insert.

The invention relates to vehicle seats and their manufacturing methods.

More specifically, the invention relates to a vehicle seat comprising a seat portion and a backrest connected to the seat portion by at least one hinge mechanism to allow adjusting the tilt of the backrest and to lock the backrest into the selected tilt angle, the seat comprising a seat element chosen from among the backrest and the seat portion, said seat element extending along a mean plane and having two sides, and said seat element comprising:

-   -   a shell of plastic material, having two lateral edges which         respectively extend along the sides of the seat element between         a first end near the hinge mechanism and a second end further         away from the hinge mechanism,     -   at least one rigid insert of composite material which is         overmolded by one of the two lateral edges of the shell of         plastic material, said rigid insert extending for a certain         length from the first end of said corresponding lateral edge,         said insert comprising resistant fibers embedded in a synthetic         matrix, and said insert presenting a U-shaped cross-section         having a core substantially perpendicular to the mean plane of         the seat element and two side flanges substantially parallel to         the mean plane of the seat element, said core being connected to         said hinge mechanism at the first end of the corresponding         lateral edge.

Document US-A-2008/038569 describes an example of a seat of this type.

One object of the invention is to improve the seats of this type, and in particular to improve the mechanical strength.

In the invention, a seat of this type is characterized by said insert being formed of two composite parts integrally attached to each other, each of said two composite parts having a L-shaped cross-section and comprising a core portion that is part of the core of the insert and one of the flanges of the insert, each of the two core portions extending for substantially the entire height of the core of the insert.

Creating the inserts in two composite parts ensures the optimum quality of the composite material in the two side flanges of each insert, which are the portions subjected to the most mechanical stress, particularly in an accident involving the vehicle. This avoids any rearrangement of the resistant fibers in these two parts during the hold molding process for the composite parts, as will be explained in more detail below.

In some embodiments of the seat of the invention, one or more of the following arrangements may be used:

-   -   the two composite parts are integrally attached to each other by         the shell of plastic material, which is overmolded onto said two         composite parts;     -   the two composite parts are integrally attached to each other by         fusion along a joining line between the core portions of the two         composite parts;     -   the two composite parts each has an overlapping strip, the two         strips being superimposed one atop the other and assembled         together by fusion along said joining line;     -   the two composite parts are integrally attached to each other by         at least one composite sheet which at least partially covers the         core portions of the two composite parts and the side flanges of         the insert;     -   the seat additionally comprises at least one metal plate which         at least partially covers the core portions of the two composite         parts and which is integrally attached to said two composite         parts, said metal plate being overmolded by the corresponding         lateral edge of the shell of plastic material and being         connected to the hinge mechanism;     -   the metal plate comprises recesses facing the two core portions         of the two composite parts and is integrally attached to each of         said core portions by the riveting formed by the penetration of         the material of these core portions into said recesses;     -   the metal plate at least partially covers the core and the two         side flanges of the insert and is also integrally attached to         said side flanges by the riveting formed by the penetration of         the material of these side flanges into recesses presented by         the metal plate facing said side flanges;     -   the metal plate is integrally attached, by a screwing         arrangement, to a rigid tab that is part of the hinge mechanism,         said metal plate having at least one support surface not encased         by the shell of plastic material, and the tab of the hinge         mechanism being supported on said support surface.

Another object of the invention is a method for manufacturing a seat as defined above, comprising at least the following steps:

(a) a composite part manufacturing step, during which the two composite parts are formed by hot pressing,

(b) an assembly step, during which the two composite parts are assembled together by their respective core portions.

In various embodiments of the method of the invention, one or more of the following arrangements may be used:

-   -   during the composite part manufacturing step (a), each composite         part is manufactured by shaping a blank comprising superimposed         composite sheets, by pressing the blank in a hot mold which         comprises two mold parts which can be moved towards each other         in a pressing direction, the side flange of the composite part         molded in this manner being substantially perpendicular to said         pressing direction;     -   during the assembly step (b), the two composite parts are         arranged so that their core portions are partially superimposed         in a certain overlapping area and said core portions are fused         together in said overlapping area by pressing in a hot mold;     -   during the assembly step (b), the two composite parts are         superimposed with a metal plate which comprises recesses and         which at least partially covers said two composite parts, and         the two composite parts are assembled together while the         material of the composite parts flows into recesses in the metal         plate, by pressing in a hot mold.

Other features and advantages of the invention will be apparent from the following description of one of its embodiments and some of its variants, provided as non-limiting examples, and the attached drawings.

In the drawings:

FIG. 1 is a side view of a seat according to one embodiment of the invention,

FIG. 2 is a perspective view of the structural framework of the backrest of the seat of FIG. 1,

FIG. 2 a is a cross-sectional view along the line IIa-IIa in FIG. 2,

FIG. 3 is an exploded perspective view showing the rigid reinforcements and the hinge mechanisms of the two sides of the seat backrest,

FIG. 4 is a detailed exploded perspective view showing the lower portion of one of the lateral reinforcements of FIG. 3,

FIG. 5 is a cross-sectional view along the line V-V in FIG. 4,

FIG. 6 is a view similar to FIG. 4, showing a portion of the lateral reinforcement of FIG. 4 viewed from another angle,

FIG. 7 is a side view showing an insert of composite material that is part of the lateral reinforcement of FIGS. 4 to 6,

FIG. 8 is a schematic view showing two composite blanks to be used in forming the insert of composite material of FIG. 7 after molding and assembly,

FIGS. 9 and 10 are schematic views illustrating the composition of the two composite blanks of FIG. 8,

FIGS. 11 and 12 are basic diagrams illustrating the hot molding of the two composite blanks of FIG. 8,

FIG. 13 is a schematic view illustrating the partially overlapping assembly of the two composite parts issuing from the molding illustrated in FIGS. 11 and 12,

and FIGS. 14 to 16 are basic diagrams illustrating some variants of the assembly of FIG. 13.

The same references are used to denote the same or similar elements in the different figures.

FIG. 1 represents a seat 1 of an automotive vehicle, for example a front seat. This seat 1 comprises a seat portion 2 which is attached to the floor of the vehicle, for example by means of rails 4 which allow adjusting the longitudinal position of the seat 1. The seat portion 2 supports a backrest 5 which may be assembled to pivot on the seat portion 2 by means of at least one hinge mechanism 6 which is controlled for example by a rotating handle 7 to adjust the tilt of the backrest 5. In the example considered here, there are two hinge mechanisms 6, arranged on each side of the seat and synchronously controlled by the handle 7 (see FIG. 2).

The backrest 5 of the seat comprises a supporting framework 5 a which is represented in FIG. 2, this framework normally being covered with foam padding which is covered on the front side with cloth, leather, or some other material.

Here, the framework 5 a of the backrest comprises a shell 8 of plastic material, particularly of polyamide and for example of polyamide 6.

As can be seen in FIG. 2, this shell 8 of plastic material may comprise, for example, a bottom 9 parallel to the mean plane of the backrest 5 and two substantially vertical lateral edges 10, forming the two sides of the backrest 5.

As represented in FIGS. 2, 2 a and 3, each of the lateral edges 10 of the shell of plastic material is overmolded onto a rigid lateral reinforcement 11 which consists of a rigid insert 12 of composite material and a metal plate 13.

The insert 12 is made of a composite material comprising resistant fibers, for example carbon fibers, embedded in a synthetic matrix such as a thermoplastic for example.

The insert 12 may be of continuous fiber reinforced thermoplastic (CFRT). Each insert 12 may, for example, have a substantially U-shaped cross-section, with a core 14 substantially perpendicular to the mean plane of the backrest and two side flanges 15 extending perpendicular to the core 14, for example outwards from the backrest.

Each insert 12 of composite material extends longitudinally for a length representing the major portion of the height of the corresponding lateral edge 10 of the shell of plastic material, extending from the lower end of said lateral edge to close to the upper end of said lateral edge in the example considered here.

As can be seen in FIGS. 2 a and 3, each plate 13 also has a U-shaped cross-section, with a core 16 partially superimposed on the core 14 of the corresponding composite insert, and two side flanges 17 partially superimposed on the side flanges 15 of the corresponding composite insert, the metal plate 13 being arranged for example inside the U-shaped cross-section formed by the composite insert 11, meaning towards the outside of the backrest in the example represented in the drawings.

Each plate 13 is integrally attached to the corresponding composite insert 12, in particular by riveting, as will be explained below. In addition, as one can see in FIG. 2 a, each lateral reinforcement 11 is also overmolded by the corresponding lateral edge 10 of the shell of plastic material, which covers the major portion of each composite insert 12 (with the possible exception of certain areas 18 that are left free, visible in FIG. 2) and each metal plate 13.

The metal plates 13 may possibly comprise attachment areas 19, visible in FIGS. 2, 2 a and 3, which are not covered by the plastic material of the shell 8. These attachment areas 19 may, for example, be formed by locally stamping bosses in the core 16 of the plates 13, and each may have, for example, two metal support surfaces 20, 21 not covered by the plastic material, on each face of the core 16 of each metal plate 13.

As one can see in FIGS. 2, 2 a and 3, the support surfaces 21 may serve as a support for the metal tabs 22 which are integrally attached to one of the plates 6 a of the corresponding hinge mechanism 6, the other plate 6 b of said hinge mechanism being fixed to the seat portion 2 of the seat. Each metal tab 22 extends substantially parallel to the core 16 of the corresponding metal plate 13 and may be attached to the metal plate 13 by a screwing attachment for example, in particular using bolts 23 which are supported by the support surfaces 20 and the external side of the corresponding metal tab 22.

As can be seen in FIGS. 4 to 7, each composite insert 12 is made of two composite parts 12 a, 12 b, each one having a substantially L-shaped cross-section and each one forming one of the side flanges 15 of the composite insert 12 and a respective portion 14 a, 14 b, of the insert core 14 of the composite insert. The two parts 14 a, 14 b of the core 14 are assembled together along a joining line 24 which extends for the entire height of the core 14. Preferably, as represented in FIG. 5, the two composite parts 12 a, 12 b are assembled together by fusion of their component composite material, in an overlapping area 25.

This overlapping area may be formed by two overlapping strips 25 a, 25 b that are respectively part of the two core portions 14 a, 14 b and which are superimposed on each other and joined by hot pressing, as will be explained below. In addition, as can be seen in FIGS. 4, 5 and 6, the metal plate 13 may have recesses 26 in its core 16 in the area of its two side flanges 17. These recesses 26, 27 contribute to integrally attaching the two composite parts 12 a, 12 b to the plate 13, by the riveting 28, 29 formed by penetration of the material of the composite parts 12 a, 12 b into said recesses 26, 27. Such riveting is obtained by the creep of the material of the composite parts 12 a, 12 b, by gluing, or by pressing in a hot mold, as will be explained below.

To summarize, the mutual attachment of the two composite parts 12 a, 12 b can therefore be obtained here by three complementary means:

-   -   the overmolding of the lateral edges 10 of the shell of plastic         material,     -   the fusion of the two composite parts 12 a, 12 b at the         overlapping strips 25 a, 25 b,     -   and riveting 28, 29.

If necessary, the integral attachment of the two composite parts 12 a, 12 b may be obtained by only one or only some of these means, or by any other means of attachment.

As represented in FIGS. 8 to 10, each of the composite parts 12 a, 12 b, constituting each composite insert 12, is made from a respective blank 30 a, 30 b consisting of a stack of sheets 31-34 of composite material. Each of the sheets 31-34 of composite material may have reinforcing fibers oriented in a predetermined direction, for example parallel to the longitudinal direction of the composite part or transverse to it. Sheets of composite material having different fiber orientations may be superimposed in predetermined sequences, in a manner that maximizes the mechanical strength of the composite parts 12 a, 12 b ultimately obtained in order to be suitable for the stresses they are intended to withstand.

As represented in FIGS. 11 and 12, the blanks 30 a, 30 b may be pressed in hot molds 35, 36 in a manner that assembles together the sheets of composite material 31, 32 to form the composite part 12 b and the sheets 33, 34 to form the composite part 12 a. The molds 35, 36 conventionally consist of two parts, respectively 35 a, 35 b and 36 a, 36 b, one 35 a, 36 a being fixed and the other 35 b, 36 b being movable in the pressing direction P. Advantageously, the molds 35, 36 are shaped so that the side flanges 15 of the two composite parts 12 a, 12 b are arranged substantially perpendicular to the pressing direction P, while the core portions 14 a, 14 b are arranged to form a relatively small angle in relation to the pressing direction P. The molds 35, 36 may for example be initially heated to a temperature of 80° C. when the blanks 30 a, 30 b are put in place, after which the molds are closed and allowed to cool during the pressing.

Thus the fibers of the side flanges 15, said flanges being the portions of the composite parts 12 a, 12 b which undergo the most stress, are not rearranged during the pressing and retain their optimal mechanical properties. Any rearrangement of the fibers which could occur in the core portions 14 a, 14 b during the hot pressing are less of a problem because the core 14 of the rigid insert 12 is the portion of this rigid insert which is subjected to the least mechanical stress.

After the composite parts 12 a, 12 b have been created by pressing in hot molds, these two parts are arranged in a hot mold 37 (previously heated for example to 80° C.), visible in FIG. 14, so that their overlapping strips 25 a, 25 b are superimposed atop one another, as represented in FIGS. 13 and 14. In addition, the plate 13 is also placed in the mold 37, then the two parts 37 a, 37 b of the mold 37 are pressed against each other in the pressing direction P which is substantially perpendicular to the core 14 of the insert. The heating of the mold is discontinued when it is closed, and the pressing is maintained while the mold cools. During this pressing operation, the abovementioned riveting 28, 29 is formed by the creep of the thermoplastic matrix of the composite into the recesses 26, 27 of the plate 13.

In a variant represented in FIG. 15, the assembly of the composite parts 12 a, 12 b can be reinforced by providing at least one supplemental composite sheet 38, which at least partially covers the core portions 14 a, 14 b of the two composite parts, for example on the side opposite the one attached to the plate 3. This layer 38 is then at least partially fused with the two core portions 14 a, 14 b during the abovementioned pressing of the hot mold 37.

In addition, as represented in FIG. 16, said composite sheet 38 may also cover the side flanges of the insert. In this case, the composite layer 38 may comprise a core 39 covering the core 14 of the insert 12 opposite the plate 13, two side flanges 40 covering the external side of the side flanges 15, and possibly two flaps 41 folded over the free edges of the side flanges 15 and 17, opposite the core 14 of the insert. These flaps 14, or one of them, may additionally be extended by a fold 42 of the composite sheet 38, which partially covers the inner face of the corresponding side flange 17 of the plate 1. The assembly represented in FIG. 16 is then hot pressed into the abovementioned mold 37.

One will note that the invention, described above for its application to the backrest of a seat, is also applicable to the seat portion. In this case, the shell 8 of plastic material would form the supporting framework of the seat portion and the lateral edges of the shell 8 of plastic material would extend along the respective sides of the seat portion between a first end (the front end) close to the hinge mechanism 6 and a second end further away from said hinge mechanism, and each rigid insert 12 of composite material would be overmolded by one of the two lateral edges 10 of the shell of plastic material, each rigid insert 12 extending for a certain length from the first end of said corresponding lateral edge. In this case as well, the core 14 of the insert 12 would be substantially perpendicular to the mean plane of the seat portion and the side flanges 15 substantially parallel to the mean plane of the seat portion, said core 14 being connected to the hinge mechanism 6 at the first end of the corresponding lateral edge. 

1. A vehicle seat comprising a seat portion and a backrest connected to the seat portion by at least one hinge mechanism to allow adjusting the tilt of the backrest and to lock the backrest into the selected tilt angle, the seat comprising a seat element chosen from among the backrest and the seat portion, said seat element extending along a mean plane and having two sides, and said seat element comprising: a shell of plastic material, having two lateral edges which respectively extend along the sides of the seat element between a first end near the hinge mechanism and a second end further from said hinge mechanism, at least one rigid insert of composite material overmolded by one of the two lateral edges of the shell of plastic material, said rigid insert extending for a certain length from the first end of said corresponding lateral edge, said insert comprising resistant fibers embedded in a synthetic matrix, and said insert presenting a U-shaped cross-section having a core substantially perpendicular to the mean plane of the seat element and two side flanges substantially parallel to the mean plane of the seat element, said core being connected to said hinge mechanism at the first end of the corresponding lateral edge, wherein said insert is formed of two composite parts integrally attached to each other, each of said two composite parts having an L-shaped cross-section and comprising a core portion that is part of the core of the insert and one of the flanges of the insert, each of the two core portions extending for substantially the entire height of the core of the insert.
 2. The seat according to claim 1, wherein the two composite parts are integrally attached to each other by the shell of plastic material, which is overmolded onto said two composite parts.
 3. The seat according to claim 1, wherein the two composite parts are integrally attached to each other by fusion along a joining line between the core portions of the two composite parts.
 4. The seat according to claim 3, wherein the two composite parts each has an overlapping strip, the two strips being superimposed atop one another and assembled together by fusion along said joining line.
 5. The seat according to claim 1, wherein the two composite parts are integrally attached to each other by at least one composite sheet which at least partially covers the core portions of the two composite parts and the side flanges of the insert.
 6. The seat according to claim 1, additionally comprising at least one metal plate which at least partially covers the core portions of the two composite parts and which is integrally attached to said two composite parts, said metal plate being overmolded by the corresponding lateral edge of the shell of plastic material and being connected to the hinge mechanism.
 7. The seat according to claim 6, wherein the metal plate comprises recesses facing the two core portions of the two composite parts and is integrally attached to each of said core portions by the riveting formed by the penetration of the material of these core portions into said recesses.
 8. The seat according to claim 6, wherein the metal plate at least partially covers the core and the two side flanges of the insert and is also integrally attached to said side flanges by riveting formed by the penetration of the material of these side flanges into recesses presented by the metal plate facing said side flanges.
 9. The seat according to claim 6, wherein the metal plate is integrally attached, by a screwing attachment, to a rigid tab that is part of the hinge mechanism, said metal plate having at least one support surface not encased by the shell of plastic material and the tab of the hinge mechanism being supported on said support surface.
 10. A method for manufacturing a seat according to claim 1, comprising at least the following steps: (a) a composite part manufacturing step, during which the two composite parts are formed by hot pressing, (b) an assembly step, during which the two composite parts are assembled together by their respective core portions.
 11. The method according to claim 10, wherein during the composite part manufacturing step (a), each composite part is manufactured by shaping a blank comprising superimposed composite sheets, by pressing the blank into a hot mold which comprises two mold parts which can be moved towards each other in a pressing direction, the side flange of the composite part molded in this manner being substantially perpendicular to said pressing direction.
 12. The method according to claim 10, wherein, during the assembly step (b), the two composite parts are arranged so that their core portions are partially superimposed in a certain overlapping area and said core portions are fused together in said overlapping area by pressing in a hot mold.
 13. The method according to claim 10, wherein, during the assembly step (b), the two composite parts are superimposed with a metal plate which comprises recesses and which at least partially covers said two composite parts, and the two composite parts are assembled together while the material of the composite parts flows into recesses in the metal plate, by pressing in a hot mold. 